Cat Heart Conditions
Cats are masters at hiding illness. Understanding feline heart conditions helps you recognize subtle signs and seek early intervention for your beloved companion.
Common Heart Diseases in Cats
These are the most frequently diagnosed cardiac conditions in our feline patients.
Hypertrophic Cardiomyopathy (HCM)
The most common heart disease in cats, causing thickening of the heart muscle and increased risk of heart failure.
Hypertrophic Cardiomyopathy (HCM) is the most common heart disease found in cats. HCM is a disease of the heart muscle that causes it to thicken. This thickened heart muscle leads to increased pressures within the heart and poor blood flow to the thickened heart muscles.
These changes increase the patient's risk for: • Spontaneous congestive heart failure (fluid building up in or around the lungs) • Development of thrombi (clots) in dilated chambers • Thromboembolism - clots that can break free and lodge into arteries supplying vital organs and/or limbs • Sudden death
A small percentage of feline patients with atrial dilation are also at risk for developing thrombi (clots) in the dilated chambers. If this occurs, the thrombus can embolize (break-free) and lodge into arteries supplying vital organs and/or limbs.
These risks are regularly assessed during each echocardiogram. If the risk is considered significant, medical therapy is recommended.
Thyrotoxic Cardiomyopathy
Heart disease caused by elevated thyroid hormone levels that can lead to heart failure if left untreated.
Thyrotoxic Cardiomyopathy is caused by metabolic disease (pathologically elevated thyroid hormone) and can lead to: • Heart failure • Cardiogenic thromboembolic disease • Sudden death
Comprehensive evaluation of the cardiac structure in patients with Hyperthyroidism can help prevent cardiac complications while the metabolic abnormalities are being treated.
The good news is that following appropriate metabolic control, often the cardiac changes are reversible. This makes early detection and treatment of both the thyroid condition and cardiac involvement essential for the best outcomes.
Rhythm Disturbances in Cats
Cardiac arrhythmias require specialized diagnosis and management.
Ventricular Arrhythmias
Ventricular arrhythmias can occur for a myriad of reasons. Primary cardiomyopathy and infiltrative disease are common causes and suspicion for this can be identified on an echocardiogram.
The underlying cause of a ventricular arrhythmia is often not determined. Intra-cardiac causes such as focal areas of the heart muscle due to fibrosis (scarring), ischemia (poor blood flow) or inflammation are not definitively identified on an echocardiogram.
Extra-cardiac causes are considered and can be due to any inflammation released into the systemic circulation. The most common extra-cardiac cause is an abnormality of the spleen (both benign as well as malignant processes).
Ventricular arrhythmias increase risk for sudden death.
AV Block
AV block is an electrical malfunction of the heart's conduction system. Normal electrical activity starts in the atrium and is conducted down to the ventricle by way of the AV node.
AV blockade can occur secondary to a structural problem of the conduction system itself or can be secondary to pathology elsewhere in the body. If conduction blockade causes the heart rate to be too slow to maintain appropriate blood flow it can lead to exercise intolerance and/or fainting.
For most cats, AV Block does not cause a significant risk for spontaneous complication. However it can be a significant risk for anesthesia. In some patients AV Block can lead to pacemaker implantation.
Congenital Heart Disease in Cats
These conditions are present from birth and may be detected during routine kitten examinations.
Ventricular Septal Defect (VSD)
A Ventricular septal defect (VSD) is the most common congenital defect in cats. A VSD is a hole caused by a malformation of the wall that separates the left and right ventricles.
When there is a hole between the ventricles, blood is allowed to re-visit the lungs and the left side of the heart without going to the body. This causes a volume and pressure overload of the left side of the heart.
Left untreated, these patients can be at risk for left-sided congestive heart failure. Evaluation by echocardiogram is important to assess this risk. Medical therapy may be indicated if there is a risk for congestive heart failure.
Patent Ductus Arteriosus (PDA)
Patent Ductus Arteriosus (PDA) is a persistent communication between the pulmonary artery and the aorta. In utero, the ductus is used to bypass the lungs because the fetus does not need to oxygenate its own blood. At birth, this ductus should close so that blood flows through the heart and lungs efficiently and effectively.
In patients with a PDA (a ductus that does not close) blood is allowed to re-visit the lungs and the left side of the heart without going to the body. This causes a volume and pressure overload of the left side of the heart.
Left untreated, most of these patients will develop left-sided congestive heart failure within the first year of life. Treatment requires surgical intervention:
• Catheter-based technique: Minimally invasive with a small incision in the groin. Uses a long catheter to place a device inside the PDA. Risk for complication is relatively low. • Thoracotomy technique: Requires surgical opening of the chest and dissection of the PDA. Usually leaves trivial flow and carries higher risk.
Unfortunately, medical therapy alone is not effective at preventing congestive heart failure in these patients. If the PDA is small, closure may not be necessary. Echocardiogram helps determine the individual complexities of patients with a PDA.
Why Early Detection Matters for Cats
Cats are exceptionally good at hiding illness. By the time symptoms become obvious, heart disease may be advanced. Regular screening echocardiograms, especially for breeds predisposed to heart disease, can catch conditions early when they're most manageable. If your cat has been diagnosed with a heart murmur or shows any signs of decreased activity, rapid breathing, or weakness, a cardiac evaluation is recommended.
Concerned About Your Cat's Heart?
Early detection can make a significant difference in managing feline heart disease. Schedule a cardiac evaluation with Dr. Ginieczki today.